The maturity of intestinal neomucosa: integrin expression and ultrastructural aspects

The maturity of neomucosa growing on a serosal surface for the treatment of short bowel syndrome still is questionable. The aim of this study was to evaluate the intestinal neomucosa to assess its histologic maturity.

A 6-cm-long isolated ileal segment (IS) was prepared in 8 Wistar albino-type rats. The IS was divided from the antimesenteric side, and 2 intestinal tubes were established, which shared a common wall and a common pedicle. After ileal biopsy sampling for the control group (CG), the IS was fashioned into a mucous fistula. Eight weeks later, all the rats were killed, and the ISs were investigated for neomucosal growth. Sections were prepared with periodic acid shift (PAS) and H & E staining for light microscopy. They also were evaluated by transmission electron microscopy. The microscopic morphology of the 2 groups was evaluated. Immunohistochemical staining was performed to show the expression of the tissue beta1, alpha3 and alpha2beta1 integrin subunits of both the neomucosa (NS) and control group (CG) segments.

Sections of the NS showed a well-arranged columnar epithelial cell layer with goblet cells that were generally located superficially and with a complete basement membrane. Under the electron microscope, the sections from the NS group showed an epithelial cell layer with proper microvilli of the same height, although they were shorter than those of the CG, and tight intercellular junctions between the epithelial cells. Significant differences between the NS and CG groups were found in the measurements of villus width at base, microvillus surface, and microvillus height. The lamina propria consisted of rich collagen fibers and active fibroblasts in the NS group. In the immunohistochemical staining, although beta1 integrine showed a dense distribution (+++) in the lamina propria, particularly localizing at the depth of the tunica mucosa layer, alpha3 integrin was observed to have a less dense immunoreactivity (++) in both groups. The expression of alpha2beta1 integrin showed slight and dispersed (+) staining.

The NS showed histologic maturity and ultimate structural similarity with the native small bowel mucosa, which provides strong indirect evidence for the proper functioning of the neomucosa.